We present the history of land use and historic vegetation conditions on the Sacramento Ranger District of the Lincoln National Forest within the framework of an ecosystem needs assessment. We reconstruct forest vegetation conditions and ecosystem processes for the period immediately before Anglo-American settlement using General Land Office survey records, historic studies and accounts, and reconstructive studies such as dendrochronological histories of fire and insect outbreak and studies of old growth. Intensive grazing, clearcut logging, fire suppression, and agriculture in riparian areas have radically altered forest structure and processes since the 1880s, when intensive settlement began in the Sacramento Mountains. Present forests are younger and more dense than historic ones, and in areas that were previously dominated by ponderosa pine, dominance has shifted to Douglas-fir and white fir in the absence of frequent surface fire. Landscapes are more homogeneous and contiguous than historic ones, facilitating large-scale, intense disturbances such as insect outbreaks and crown fires.

An approach for synthesizing the results of ecological research pertinent to land management is the analysis of the historic range of variability (HRV) for key ecosystem variables that are affected by management activities. This report provides an HRV analysis for the upland vegetation of the Bighorn National Forest in northcentral Wyoming. The variables include live tree density, dead tree (snag) density, canopy cover, abundance of coarse woody debris, species diversity, fire return intervals, the abundance of various diseases, the proportion of the landscape in different land cover types, and the degree of patchiness in the landscape. The variables were examined at the stand and landscape scales, using information available in the literature and USFS databases. High-elevation landscapes were considered separately from low-elevation landscapes. Much of the report pertains to forests dominated by lodge-pole pine, subalpine fir, and Engelmann spruce at high elevations, and by ponderosa pine, aspen, and Douglas-fir at lower elevations. We defined the HRV reference period for the BNF as approximately 1600 to 1890.